Keep local libraries in mind too, particularly documents. Maybe you don't have something stunning that the Smithsonian, CRRM or DPL is dying for, but say you happen to have a lot of pictures of stuff at Craig, CO. Consider seeing if the library there would like it.
Not only would it be more likely to actually be carefully cataloged, it might just help school kids there learn about their heritage. Kids are more savvy than you think about history, but they have to have opportunity, and someone has to trust that its ok to let them hold and study something special.
Philip